KR20180049991A - Pump tower of lng storage tank and operating method of this at emergency time - Google Patents

Abstract

The present invention relates to a pump tower of an LNG storage tank, and an operating method thereof in emergency. According to the present invention, a conventional charging pipe is removed and an emergency column is used as a charging pipe. Moreover, a support unit can respond to a rapid change of impact load and temperature at a lower end portion of the emergency column. In the emergency column, a fool valve assembly is disposed to be lifted up and down. In addition, a switching unit can be provided to enable the emergency column to be switched and used for emergency or charging. Therefore, infrequent elements can be switched to be used, and a volume of the entire pump tower can be reduced to increase efficiency in space utilization.

Description

TECHNICAL FIELD [0001] The present invention relates to a pump tower of an LNG storage tank and an emergency operation method of the same.

The present invention relates to a pump tower of an LNG storage tank and an emergency operation method thereof. More particularly, the present invention relates to a pump tower for use in an LNG storage tank, The present invention relates to a pump tower of an LNG storage tank and an emergency operation method thereof.

A typical pump tower is composed of two discharge pipes, one filling pipe, and an emergency column, which can be used in emergency situations where the aforementioned discharge pipe is not operating normally.

A common pump tower, such as the "pump tower structure of an LNG storage tank" (hereinafter "prior art") of Laid-Open Patent No. 10-2015-0069084, is used to store an LNG in order to unload a liquid cargo such as LNG contained in a liquefied natural gas storage tank It is a structure installed inside the tank.

In other words, the structure of a general pump tower is a tripod in the form of two discharge pipes and one emergency column, and the charging pipe is a batch structure attached to the emergency column.

However, the conventional pump tower including the prior art has a structure in which the charging pipe for charging the LNG is disposed separately on the outside of the emergency column, as compared with the emergency column in which the frequency of use is very low. Therefore, There was a problem.

Published Japanese Patent Application No. 10-2015-0069084

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a pump tower of an LNG storage tank and an emergency operation method of the pump tower.

In addition, the present invention provides a pump tower of an LNG storage tank and an emergency operation method of the pump tower, which can reduce the volume of the entire apparatus to improve the efficiency of space utilization.

The present invention also provides a pump tower of an LNG storage tank and an emergency operation method thereof, which can maintain high durability and reliability of the entire apparatus while adding a configuration for use in other parts to existing components.

In order to achieve the above-mentioned object, the present invention provides a LNG storage tank, wherein the LNG storage tank is disposed at a predetermined height and spaced apart from a pair of discharge pipes having an inner diameter of a first diameter by the same distance, An emergency column having an inner diameter of a second diameter larger than the diameter and installed at a predetermined height in the LNG storage tank; Wherein when the emergency column is used as a flow path for charging the LNG from the outside through the LNG storage tank, the membrane of the LNG storage tank is protected from a sudden change in load and temperature applied toward the bottom surface of the LNG storage tank when the LNG is charged A support unit provided at a lower end of the emergency column and connected to a bottom surface of the LNG storage tank; And the liquefied natural gas (LNG) storage tanks are selectively allowed to communicate with each other, so as to discharge the LNG from the LNG storage tank to the outside, when the LNG storage tank is normally emptied on the upper side of the emergency column, Or shut off; And a switching unit for lifting the foot valve assembly to switch the emergency column for charging the LNG or for emergency pumping of the LNG.

Here, the emergency column may include an N2 port provided on an outer circumferential surface of an upper end of the emergency column for injecting nitrogen gas, a lower N2 port provided on an upper outer peripheral surface of the emergency column, The LNG storage tank being connected to the LNG storage tank to supply the LNG to the tank, and a charging pipe connected to the LNG storage tank to discharge the LNG from the LNG storage tank, And an emergency discharge pipe connected to the outside to discharge the LNG, wherein the foot valve assembly is normally disposed in a space between the N2 port and the charging pipe.

The support unit may include a support rod disposed at a plurality of spaced distances along a lower end edge of the emergency column, a support rod connected to a lower end of each of the plurality of support rods, facing the lower surface of the emergency column, Wherein the foot valve assembly is lowered to an upper surface of the pedestal piece in an emergency so that the LNG storage tank and the lower end of the emergency column communicate with each other.

The foot valve assembly includes a stopper having an outer diameter smaller than an inner diameter of the emergency column and capable of contacting the upper surface of the support piece of the support unit when the emergency valve is lowered in an emergency state, A guide rod which is parallel to the inner circumferential surface of the guide rod, a valve body which is mounted on the guide rod so as to ascend and retract along the guide rod and which passes through both ends of the guide rod, And a biasing means which is mounted for each of the guide rods and is disposed between the finishing piece and the valve body and permits elastic deformation due to the reciprocating movement of the valve body, And the foot valve assembly is lifted and retracted.

The foot valve assembly further includes a first sealing pad mounted on a bottom surface of the stop piece and having an outer diameter larger than that of the stop piece and maintaining airtightness with the inner circumferential surface of the emergency column.

The valve body is formed in a cylindrical shape having upper and lower ends at both ends and has an elevating portion having an outer diameter smaller than the inner diameter of the emergency column and a flange portion extending radially inward along the lower end edge of the elevating portion, A rim-shaped seat flange which is in contact with or contacts with the guide rod, and a bottom surface which is engaged with an upper end of the elevating portion, and which has an outer diameter larger than the outer diameter of the elevating portion and smaller than an inner diameter of the emergency column, And a rim-shaped cover flange that contacts or faces the top surface of the convenience,

And the lower end of the biasing means is in contact with the upper surface of the seat flange.

A seat positioning flange extending inwardly from a lower end edge of the emergency column and having a cover flange of the valve body lowered to which the lower flange is fixed; And a plurality of temporary fixing springs which fix the upper surface edge of the fixing member.

The valve body may further include a second sealing pad mounted on an outer circumferential surface of the cover flange to maintain airtightness between the inner circumferential surfaces of the emergency column.

And a plurality of temporary fixing springs protrudingly formed on the upper side of the inner circumferential surface of the emergency column to allow elastic deformation and fix the outer flange of the lift flange to be engaged or fixed.

The switching unit includes a hatch cover that is detachably coupled to an upper end of the emergency column and covers an upper surface of the emergency column, a coupling hole that is coupled through the hatch cover and is detachably coupled to the upper surface of the foot valve assembly And a lift plate disposed at an upper end of the emergency column in place of the hatch cover in an emergency, and a lifting / lowering wire which is wound or unwound by passing through the replacement plate, And an emergency pump connected to a lower end of the LNG storage tank and lowered to an upper surface of the foot valve assembly lowered to a bottom surface side of the LNG storage tank.

In addition, the valve moving unit includes a moving screw that is threaded through a central portion of the hatch cover so as to move forward and backward, thereby elevating and lowering the connecting port.

According to another aspect of the present invention, there is provided an LNG storage tank, comprising: a first step of lowering a foot valve assembly built in an upper part of an emergency column installed at a predetermined height inside an LNG storage tank to a bottom surface of the LNG storage tank; A second step of injecting nitrogen gas into the internal space of the emergency column to discharge all of the LNG remaining in the emergency column to the LNG storage tank; The injection of the nitrogen gas is stopped so that the foot valve assembly interrupts the communication between the LNG storage tank and the emergency column due to the elastic repulsive force of the biasing means of the foot valve assembly and the pressure due to the head of the LNG storage tank A third step of lowering the emergency pump from the upper end of the emergency column to the upper surface of the foot valve assembly; And a fourth step of injecting nitrogen gas again to remove remaining LNG in the emergency column when the power connection of the emergency pump and the accurate seating position of the foot valve assembly are determined, and then operating the emergency pump To provide an emergency operating method of the pump tower of the LNG storage tank.

According to the present invention having the above-described configuration, the following effects can be achieved.

First, the present invention removes the existing filling pipe and uses the emergency column as a fill pipe, with the support unit being adapted to respond to a sudden change in impact load and temperature at the lower end of the emergency column, And a switching unit is provided so that the emergency column can be switched to be used for emergency or charging so that an emergency column having a lower frequency of use than a pair of discharge pipes and existing filling pipes can be used as a filling pipe So that the efficiency of operation of the apparatus can be improved.

Further, the present invention eliminates the existing filling pipe and serves as an emergency column for emergency discharge and filling, thereby reducing the volume of the entire apparatus, thereby securing a space occupied by the existing filling pipe as an additional cargo loading space The efficiency of space utilization can also be improved.

Further, the present invention can maintain high reliability and durability of the entire apparatus even though various constitutions of the switching unit are added to the existing emergency column for use as a filling pipe, thereby enabling delivery of a reliable product to the consumer will be.

FIG. 1 is a conceptual diagram showing the overall configuration of a pump tower of an LNG storage tank according to an embodiment of the present invention. FIG. 1 (a) Fig. 5 is a diagram showing a cross-sectional conceptional view showing the above.
FIG. 2 is a cross-sectional view of a foot valve assembly, which is a main part of a pump tower of an LNG storage tank according to an embodiment of the present invention, It is a conceptual diagram.
FIG. 3 is a cross-sectional view of a foot valve assembly, which is a main part of a pump tower of an LNG storage tank according to an embodiment of the present invention, illustrating a flow path opening state allowing communication between a lower end of an emergency column and an LNG storage tank. It is a conceptual diagram.
FIGS. 4 to 10 are schematic cross-sectional views illustrating an emergency operation method of a pump tower of an LNG storage tank according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings.

However, the present invention is not limited to the embodiments described below, but may be embodied in various other forms.

The present embodiments are provided so that the disclosure of the present invention is thoroughly disclosed and that those skilled in the art will fully understand the scope of the present invention.

And the present invention is only defined by the scope of the claims.

Thus, in some embodiments, well known components, well known operations, and well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention.

In addition, throughout the specification, like reference numerals refer to like elements, and the terms (mentioned) used herein are intended to illustrate the embodiments and not to limit the invention.

In this specification, the singular forms include plural forms unless the context clearly dictates otherwise, and the constituents and acts referred to as " comprising (or having) " do not exclude the presence or addition of one or more other constituents and actions .

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs.

Also, commonly used predefined terms are not ideally or excessively interpreted unless they are defined.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram showing the overall configuration of a pump tower of an LNG storage tank according to an embodiment of the present invention. FIG. 1 (a) Fig. 5 is a diagram showing a cross-sectional conceptual diagram showing what is seen.

FIG. 2 is a cross-sectional view of a foot valve assembly, which is a main part of a pump tower of an LNG storage tank according to an embodiment of the present invention, It is a conceptual diagram.

FIG. 3 is a cross-sectional view of a foot valve assembly, which is a main part of a pump tower of an LNG storage tank according to an embodiment of the present invention, illustrating a flow path opening state allowing communication between a lower end of an emergency column and an LNG storage tank. It is a conceptual diagram.

FIGS. 4 to 10 are schematic cross-sectional views illustrating an emergency operation method of a pump tower of an LNG storage tank according to an embodiment of the present invention.

For reference, in FIGS. 4 to 6, FIG. 9 and FIG. 10, it is N2 gas marked '*' in the inside of the emergency column 10, and LNG is displayed in '

The present invention is based on the use of an emergency column 10 as a filling pipe in which the support unit 30 is placed under the influence of a sudden change in impact load and temperature at the lower end of the emergency column 10 A structure in which the foot valve assembly 40 can be elevated inside the emergency column 10 and the switching unit 50 is provided so that the emergency column 10 can be used for emergency or charging .

The emergency column 10 is disposed at a predetermined height inside the LNG storage tank (not shown) and spaced apart from a pair of discharge pipes 20 having an inner diameter of the first diameter by the same distance, Has an inner diameter of a second diameter larger than the first diameter, and is installed at a certain height inside the LNG storage tank.

When the emergency column 10 is used as a flow path for charging the LNG from the outside through the LNG storage tank, the support unit 30 can be installed in the LNG storage tank 10 from the sudden load and temperature changes toward the bottom surface of the LNG storage tank, And is connected to the bottom surface of the LNG storage tank at the lower end of the emergency column 10 to protect the membrane of the LNG storage tank.

The foot valve assembly 40 is normally installed on the upper side of the emergency column 10 and descends to the lower end of the emergency column 10 in an emergency so as to discharge the LNG from the LNG storage tank to the outside. Thereby selectively allowing or blocking the communication between the LNG storage tanks.

The switching unit 50 is to raise and lower the foot valve assembly 40 to switch the emergency column 10 for charging the LNG or for emergency pumping of the LNG.

It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention.

First, the emergency column 10 may further include an N ₂ port 11 provided on the outer peripheral surface of the upper end of the emergency column 10, into which nitrogen gas is injected.

The N ₂ port 11 provides a passage through which the nitrogen gas as the inert gas and the stabilizing gas is injected so that the remaining LNG in the emergency column 10 due to the detachable coupling of the switching unit 50, And to provide an injection path for the nitrogen gas injected into the stabilizing operation to prevent leakage to the outside through the upper end.

The emergency column 10 is provided on the upper side outer peripheral surface of the emergency column 10 and is disposed on the lower side of the N2 port 11 and is connected to a charging pipe 12 ).

The emergency column 10 is provided on the upper side outer peripheral surface of the emergency column 10 and disposed on the lower side of the N2 port 11 and is disposed in a straight line with the charging pipe 12, And an emergency discharge pipe (13) connected to discharge the LNG to the emergency side.

Here, the foot valve assembly 40 is normally disposed in the space between the N ₂ port 11 and the charging pipe 12 for convenience of storage and management.

At this time, a filling valve 12f is mounted on the filling pipe 12 to open and close the flow path of the filling pipe 12. An emergency valve 13e is mounted on the emergency discharging pipe 13 to connect the emergency discharging pipe 13, As shown in Fig.

The charging valve 12f and the emergency valve 13e are used for switching between the use of the charging pipe and the emergency discharging operation of the LNG after a series of replacement by the switching unit 50 to be described later, And the like.

The support unit 30 includes a support rod 31 disposed at a plurality of spaced apart positions along the lower end edge of the emergency column 10 and an emergency column 10 connected to a lower end of each of the plurality of support bars 31 And a support piece 32 disposed in contact with the bottom surface of the LNG storage tank while facing the lower surface of the LNG storage tank.

Here, the support unit 30 allows the LNG to be unloaded through the support piece 32 connected by the support rod 31, so that the physical and chemical impacts due to the sudden temperature change and the impact load are directly applied to the bottom surface of the LNG storage tank To prevent the transmission of information.

At this time, the foot valve assembly 40, which will be described later, descends to the upper surface of the support piece 32 in an emergency so as to communicate the LNG storage tank and the lower end of the emergency column 10 with each other.

2 and 3, the foot valve assembly 40 includes a biasing member 45 fixed to the guide rod 42 of the stopper 41 by a finishing piece 44, The valve body 43 capable of being elevated by the deformation serves to communicate or block the LNG storage tank and the lower end portion of the emergency column 10 with each other.

The stopper 41 is lowered in an emergency and can contact the upper surface of the support piece 32 of the support unit 30. The stopper 41 has an outer diameter smaller than the inner diameter of the emergency column 10 and is provided with a guide rod 42 Space.

The guide rod 42 is disposed radially on the stopper 41 and is disposed in parallel with the inner circumferential surface of the emergency column 10 so as to be connected to a valve body 43 to be described later and a biasing means 45 And a finishing piece 44 to be described later is provided to provide a space and an area to be mounted on the upper end of the guide rod 42.

The valve body 43 is mounted on the guide rod 42 so as to be capable of ascending and retreating and is vertically reciprocated so that the LNG storage tank and the emergency column 10 The lower end portions of the first and second openings are mutually communicated or blocked.

The closing piece 44 is provided at the upper end of the guide rod 42 and is provided for the purpose of locking the valve body 43 to restrict the deviation due to the excessive rise of the valve body 43.

The biasing means 45 is provided for each of the guide rods 42 and is disposed between the closing piece 44 and the valve body 43 and permits elastic deformation due to the reciprocating movement of the valve body 43, A member such as a coil spring can be mounted.

The switching unit 50, which will be described later, is detachably coupled to the upper side of the valve body 43 to move the foot valve assembly 40 up and down.

Meanwhile, in order to maintain the airtight state of the foot valve assembly 40 so that the remaining LNG does not leak from the lower side of the emergency column 10 when the nitrogen gas is stabilized in the operation method described later, 46a.

That is, the first sealing pad 46a is mounted on the bottom surface of the stopper piece 41 and has an outer diameter larger than that of the stopper piece 41 to maintain airtightness with the inner peripheral surface of the emergency column 10. [

The first sealing pad 46a can also perform a function of relieving the shock when the valve body 43 is lowered to the stopper piece 32 of the support unit 30 by the switching unit 50 to be described later Of course it is.

On the other hand, the valve body 43 is formed into a columnar shape having both upper and lower ends through which the seat flange 43b, the cover flange 43c, and the like are fitted to the elevating portion 43a having an outer diameter smaller than the inner diameter of the emergency column 10 It can be understood that the structure is provided.

The seat flange 43b is a rim-shaped member that extends radially inwardly along the lower end edge of the elevating portion 43a and opposes or comes into contact with the stopping piece 41 and the guide rod 42 penetrates .

The cover flange 43c forms a bottom surface coupled to the upper end of the lift portion 43a and has an outer diameter larger than the outer diameter of the lift portion 43a and smaller than the inner diameter of the emergency column 10, Like members that are in contact with or face each other.

Therefore, it can be understood that the lower end of the biasing means 45 is in contact with the upper surface of the seat flange 43b.

In order to prevent the foot valve assembly 40 from completely falling off through the lower end portion of the emergency column 10 when the foot valve assembly 40 is lowered during descent of the foot valve assembly 40 and sinking to the bottom surface of the LNG storage tank, (14) and a temporary fixing spring (15).

At this time, the seat positioning flange 14 and the temporary fixing spring 15 are located at a predetermined position in a state in which the valve body 43 of the foot valve assembly 40 is locked in the fixed position and the LNG storage tank and the emergency column 10 Thereby facilitating the operation of mutually communicating or blocking the lower end portion.

The seat positioning flange 14 extends inward from the lower end edge of the emergency column 10 and the cover flange 43c of the lowered valve body 43 is engaged and fixed.

The plurality of temporary fixing springs 15 are mounted on the lower side of the inner circumferential surface of the emergency column 10 to allow elastic deformation and to fix the top edge of the cover flange 43c.

Needless to say, the valve element 43 may further include a second sealing pad 46b mounted on the outer peripheral surface of the cover flange 43c to maintain airtightness between the inner peripheral surfaces of the emergency column 10 .

In addition, the present invention, in conjunction with the provisional fixing spring 15 on the lower side of the emergency column 10 as described above, is protruded on the upper side of the inner circumferential surface of the emergency column 10 to allow elastic deformation, And a plurality of temporary fixing springs 15 for fixing the outer circumferential surface of the elevating portion 43a to be contact-fixed.

On the other hand, the switching unit 50 includes a hatch cover 51 (see Fig. 1) that is detachably engaged with the upper end portion of the emergency column 10 and covers the upper surface of the emergency column 10, And a valve moving part 52 (see FIG. 4) provided with a connection port 52c to be detachably engaged with the upper surface of the foot valve assembly 40 and lowering the foot valve assembly 40 to the lower end side of the emergency column 10 ).

The switching unit 50 includes a replacement plate 53 (see FIG. 8) disposed in the upper end portion of the emergency column 10 in place of the hatch cover 51 in an emergency, And an emergency pump 54 connected to a lower end of a lift wire 55 (refer to FIG. 8) to be lowered to an upper surface of the foot valve assembly 40 lowered to a bottom surface side of the LNG storage tank.

The upper end of the lifting wire 55 may be connected to a hook 56 (see FIG. 8) of the crane as shown in the drawing, or may be connected to a wire winch (not shown) will be.

At this time, the valve moving part 52 may include a moving screw 52s which passes through the center of the hatch cover 51 and is screwed in a forward / reverse rotatable manner to move the connecting hole 52c up and down.

Hereinafter, an emergency operation method of the pump tower of the LNG storage tank according to an embodiment of the present invention will be described with reference to FIGS. 4 to 10 as follows.

For reference, reference numerals not shown in Figs. 4 to 10 refer to Figs. 1 to 3. Fig.

First, the operator puts the foot valve assembly 40, which is embedded as shown in FIG. 4, on the upper side of the emergency column 10 installed at a predetermined height inside the LNG storage tank, to lower the floor of the LNG storage tank (S1: first step).

The lowering of the foot valve assembly 40 is performed by unidirectionally screwing the connecting screw 52c connected to the upper surface of the foot valve assembly 40 to the lower end of the foot valve assembly 40 as shown in FIGS. do.

Thereafter, the connecting state between the connector 52c and the foot valve assembly 40 is released and the moving screw 52s is screw-rotated in the reverse direction so as not to interfere with the injection of the nitrogen gas to be performed in the second step S2 to be described later As shown in FIG.

Subsequently, the operator injects nitrogen gas into the internal space of the emergency column 10 as shown in FIG. 7 to discharge all of the LNG remaining in the emergency column 10 to the LNG storage tank (S2: Step 2).

The injection of the nitrogen gas is stopped so that the foot valve assembly 40 is moved to the LNG storage tank 40 by the resilient repulsive force of the biasing means 45 of the foot valve assembly 40 and the pressure due to the head of the LNG storage tank. The communication of the emergency column 10 is interrupted (see the state of the foot valve assembly 40 at the lower end of Fig. 7).

At this time, the operator separates the hatch cover 51 together with the valve moving part 52 and moves the emergency pump 54 from the upper end of the emergency column 10 to the upper surface of the foot valve assembly 40 (Step S3: step 3).

Subsequently, when the power connection of the emergency pump 54 and the accurate seating position of the foot valve assembly 40 are determined, nitrogen gas is injected again as shown in FIG. 9 to remove residual LNG in the emergency column 10, 10, the emergency pump 54 is operated to discharge the LNG (S4: fourth step)

Hereinafter, operational effects according to various embodiments of the present invention will be described.

First, the present invention eliminates the existing filling pipe and uses the emergency column 10 as a fill pipe, with the support unit 30 responding to a sudden change in impact load and temperature at the lower end of the emergency column 10 The foot valve assembly 40 can be elevated within the emergency column 10 and the switching unit 50 can be provided so that the emergency column 10 can be used for emergency or charging, The emergency column 10 having a lower frequency of use than the discharge pipes 10 and 10 and the existing filling pipe can be switched to the use of the filling pipe and the efficiency of the device operation can be improved.

In addition, the present invention eliminates the existing filling pipe and also serves as an emergency column 10 for emergency discharge and filling, thereby reducing the volume of the entire apparatus and securing the space occupied by the existing filling pipe as an additional cargo loading space So that the efficiency of space utilization can be improved.

In addition, the present invention can maintain high durability and reliability of the entire apparatus even though various constitutions of the switching unit 50 are added to the existing emergency column 10 for use as a filling pipe, Will be possible.

As described above, the present invention can reduce the volume of the entire apparatus by increasing the efficiency of space utilization and improve the durability and the overall efficiency of the apparatus, The pump tower of the LNG storage tank and the emergency operation method of the pump tower are provided as basic technical ideas.

It will be apparent to those skilled in the art that many other modifications and applications are possible within the scope of the basic technical idea of the present invention.

10 ... Emergency column
11 ... N ₂ port
12 ... charging piping
12f ... charging valve
13 ... Emergency discharge piping
13e ... emergency valve
14 ... seat positioning flange
15 ... temporary fixing spring
20, 20 ... exhaust pipe
30 ... support unit
31 ... support rod
32 ... pedestal
40 ... foot valve assembly
41 ... Stop
42 ... guide rod
43 ... valve body
43a ... elevating portion
43b ... seat flange
43c ... cover flange
44 ... Closed piece
45 ... biasing means
46a ... first sealing pad
46b ... second sealing pad
50 ... switching unit
51 ... Hatch cover
52 ... valve moving part
52c ... connector
52s ... Moving screw
53 ... Replacement plate
54 ... emergency pump
55 ... lifting wire
56 ... hook
LV ... LNG level
S1 ... Step 1
S2 ... Step 2
S3 ... Step 3
S4 ... Step 4

Claims (12)

A plurality of discharge pipes arranged at equal distances from a pair of discharge pipes having an inner diameter of a first diameter and disposed at equal heights inside the LNG storage tank and having an inner diameter of a second diameter larger than the first diameter, An emergency column installed at a predetermined height inside the LNG storage tank;
Wherein when the emergency column is used as a flow path for charging the LNG from the outside through the LNG storage tank, the membrane of the LNG storage tank is protected from a sudden change in load and temperature applied toward the bottom surface of the LNG storage tank when the LNG is charged A support unit provided at a lower end of the emergency column and connected to a bottom surface of the LNG storage tank;
And the liquefied natural gas (LNG) storage tanks are selectively allowed to communicate with each other, so that the LNG is discharged from the LNG storage tanks to the outside by being lowered to the lower ends of the emergency columns in an emergency. Or shut off; And
And a switching unit for lifting the foot valve assembly to switch the emergency column for charging the LNG or for emergency pumping of the LNG. The method according to claim 1,
Wherein the emergency column comprises:
An N2 port provided on the outer peripheral surface of the upper end of the emergency column for injecting nitrogen gas,
A charging pipe provided on an upper side outer peripheral surface of the emergency column and disposed on a lower side of the N2 port and connected to charge the LNG from the outside to the LNG storage tank side,
An emergency discharge pipe provided on an upper side outer peripheral surface of the emergency column and disposed on a lower side of the N2 port and disposed in a straight line with the filling pipe, and connected to discharge the LNG from the LNG storage tank to the outside, Further comprising:
Wherein the foot valve assembly is normally disposed in a space between the N2 port and the charge piping. The method according to claim 1,
The support unit includes:
A support rod disposed at a plurality of locations along the lower edge of the emergency column;
And a support piece connected to a lower end of each of the plurality of support bars and disposed in contact with a bottom surface of the LNG storage tank while facing a lower surface of the opened emergency column,
Wherein the foot valve assembly is lowered to an upper surface of the pedestal piece in an emergency so that the LNG storage tank and the lower end of the emergency column communicate with each other. The method according to claim 1,
The foot valve assembly includes:
A stopper which is lowered in an emergency and can contact the upper surface of the support piece of the support unit and has an outer diameter smaller than the inner diameter of the emergency column,
A guide rod disposed radially on the stop piece and parallel to the inner circumferential surface of the emergency column,
A valve body mounted vertically and reciprocably along the guide rod,
A finishing piece provided at an upper end of the guide rod for regulating a departure due to an excessive rise of the valve body,
And biasing means which is mounted for each of the guide rods and is disposed between the finishing piece and the valve body and permits elastic deformation due to the reciprocating movement of the valve body,
Wherein the switching unit is detachably coupled to an upper side of the valve body so as to reciprocate the lifting and lowering of the foot valve assembly. The method of claim 4,
The foot valve assembly includes:
Further comprising a first sealing pad mounted on a bottom surface of the stopping piece and having an outer diameter larger than that of the stopping piece and maintaining airtightness with the inner circumferential surface of the emergency column. The method of claim 4,
Wherein the valve body comprises:
An elevating portion formed in a columnar shape of upper and lower ends at both ends and having an outer diameter smaller than an inner diameter of the emergency column,
A rim-shaped seat flange extending radially inwardly along a lower end edge of the elevating portion and facing or contacting the stopping piece, the guide rod extending through the seat flange;
And a rim-shaped cover flange having an outer diameter larger than the outer diameter of the elevating portion and smaller than an inner diameter of the emergency column and contacting or facing the upper surface of the finishing piece,
And the lower end of the biasing means is in contact with the upper surface of the seat flange. The method of claim 6,
A seat positioning flange extending inward from a lower end edge of the emergency column and having a cover flange of the valve body lowered,
Further comprising: a plurality of temporary fixing springs mounted on the lower side of the inner circumferential surface of the emergency column to allow elastic deformation and to fix the upper surface edge of the cover flange by latching. The method of claim 6,
Wherein the valve body comprises:
And a second sealing pad mounted on an outer circumferential surface of the cover flange to maintain airtightness between the inner circumferential surfaces of the emergency column. The method of claim 6,
Further comprising a plurality of temporary fixing springs protrudingly formed on the upper side of the inner circumferential surface of the emergency column to permit elastic deformation and to normally fix the cover flange or fix the outer circumferential surface of the elevating portion to be contacted and fixed. Of pump tower. The method according to claim 1,
The switching unit includes:
A hatch cover detachably coupled to the upper end of the emergency column and covering an upper surface of the emergency column,
A valve moving unit coupled to the hatch cover and coupled to the foot valve assembly and detachably coupled to an upper surface of the foot valve assembly, the valve moving unit lowering the foot valve assembly to a lower end of the emergency column,
A replacement plate disposed in an upper end portion of the emergency column instead of the hatch cover in an emergency,
And an emergency pump connected to a lower end of the lifting wire that is wound or unwound through the replacement plate and descends to an upper surface of the foot valve assembly lowered to a bottom surface side of the LNG storage tank. Pump tower. The method of claim 9,
The valve-
And a moving screw which is threaded through the center of the hatch cover so as to be able to rotate forward and backward to elevate the connecting port. A first step of lowering the foot valve assembly built in the upper side of the emergency column installed at a predetermined height inside the LNG storage tank to the bottom surface of the LNG storage tank;
A second step of injecting nitrogen gas into the internal space of the emergency column to discharge all of the LNG remaining in the emergency column to the LNG storage tank;
The injection of the nitrogen gas is stopped so that the foot valve assembly interrupts the communication between the LNG storage tank and the emergency column due to the elastic repulsive force of the biasing means of the foot valve assembly and the pressure due to the head of the LNG storage tank A third step of lowering the emergency pump from the upper end of the emergency column to the upper surface of the foot valve assembly;
And a fourth step of injecting nitrogen gas again to remove remaining LNG in the emergency column when the power connection of the emergency pump and the accurate seating position of the foot valve assembly are determined, and then operating the emergency pump Of the pump tower of the LNG storage tank.

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